Two-dimensional Euler grid approximation method for multi-droplet motions

Abstract

Multi-droplet motion in gas flow is a significant two-phase flow in nuclear power plant, chemical industry and environmental engineering. In contrast to droplet generation and collision in microscopic view, multi-droplet motion presents both macroscopic interaction with gas flow and microscopic single droplet motion characteristic. To simulate the multi-droplet motion, we presented the Euler grid approximation method to update the multi-droplet imformation in all nodes under each calculation step, and constructed a criterion about droplet velocity and direction to ensure droplet motion limited on grid nodes without loss of accuracy. The novelty of this method lies in its description of the virtual streamlines of multiple particles in the same state, as well as the discontinuous flow field composed of these virtual streamlines, furthermore, this method is independent of the time step and can simultaneously calculate droplet information of the entire field. Meanwhile, this paper focuses on the two-phase gas-liquid flow in the gravity separation space of the rotary vane separator, and the motion behavior of multiple droplets in the flow field is simulated based on the parameters of the actual steam-water separator.The result shows that the droplets tend to gather towards the center of the main stream, which is the focus area for droplet separation, and the position with higher density may be the point where the droplets collide. The model can be adopted to calculate the separation efficiency in the process of multi-droplet motion in the gravity separation space, rotary vane separator and other steam separation devices, and the results will help guide the optimal design of the separation device structure.